B is the verified answer; the selection shown in the candidate PDF is not reliable here. The difficulty is that FullName contains a variable number of space delimiters. A simple “split all” operation would produce First | Last for a two-part name but First | Middle | Last for a three-part name, so the second result column does not consistently represent the middle name. Tableau’s Custom Split functionality allows splitting from the first or last occurrences of a delimiter. The analyst can therefore reliably extract the first and last names regardless of whether a middle name exists, and derive the middle component when present. Tableau’s documentation notes that Custom Split provides control over first N, last N, or all occurrences and is useful when separator counts vary between records.